The Viral Epidemiology Branch (VEB) has used a variety of approaches to define the nature and magnitude of HIV-1 associated malignancies, including analyses of population-based data, prospective cohort studies, and laboratory investigations. Our current work has focused on Kaposi's sarcoma and its associated herpesvirus, HHV-8. We evaluated four enzyme-linked immunoassays (EIAs) and one immunofluorescence assay (IFA) for HHV-8 antibodies using sera from 87 Kaposi's sarcoma patients and 210 hemophilia patients, and found that no single test had both sensitivity and specificity above 90%, but a combination of two of these tests had between 80% and 90% sensitivity and 95% and 100% specificity. We also identified a hyperendemic population in Brazil in which the HHV-8 strain was a novel sub-type. Analysis of the AIDS-Cancer Match Registry showed that although invasive cervical and anal cancers occurred in excess, they were not associated with time-of-AIDS and thus not with immune suppression; in contrast, in situ cancers did appear to increase with level of immune suppression. In another analysis, we identified T-cell lymphoma as an additional immunophenotype increased in HIV-infection. Analysis of match data for children with AIDS found that the spectrum of AIDS-associated pediatric cancers is similar to that seen in adults, with the addition of leiomyosarcoma. We also collaborated on an international meta-analysis of AIDS cohort studies which revealed declining incidence of Kaposi's sarcoma and non-Hodgkin's lymphoma, but not of other malignanies.